by Les Saidel - December, 2013
Baking in different seasons presents challenges to the baker. Climate probably affects other craftsmen, such a carpenters (wood is sensitive to humidity levels and temperature), but I believe that no other craftsman is more at the mercy of the elements than the baker.
The factor that is most "problematic" in relation to climate is yeast. This living organism, like all living organisms, responds and behaves differently to climate fluctuations.
Yeast is very much a lover of warm and sunny climes. It metabolizes and reproduces most efficiently at a temperature of approximately 27 degrees C. At temperatures lower than this it performs sluggishly and as temperature is reduced further, below 15 degrees C, the yeast cells gradually go into a state of dormancy or hibernation. More extreme temperatures, on both ends of the scale, can kill the yeast cells, below -10 degrees C and above 40 degrees C.
Not surprisingly therefore you will have noticed that dough rises quicker in summer than in winter. In fact summer is a time of playing "catch up" with your dough, trying to keep pace with its accelerated rising. In winter, on the other hand, you will find the dough sluggish, taking forever to rise.
Home bakers often have the "luxury" of philosophically bearing these changes in rising time, but professional bakers on a tight schedule cannot. Fortunately there is a simple trick or two that professional bakers use to achieve consistency in their dough behavior, regardless of the climate, which you can also use at home.
The temperature of the dough is determined firstly by the temperature of the ingredients and finally by the ambient/room temperature. The temperature of the ingredients determines the initial temperature of the dough and over time, (depending on the length of rising time), the room temperature determines the final dough temperature - more markedly so in dough that has an extended rising time (like sourdough).
It is very difficult to alter the temperature of all the ingredients in dough except for water. You could try warming flour, salt and yeast in the microwave before mixing your dough, but you could easily end up with a chemistry experiment gone awry. Water temperature on the other hand is easy to play with. You can heat it up (in a kettle), cool it down (with ice) without much bother or risk of damaging the ingredient irreparably. It is the water component of the dough therefore that professional bakers play with in terms of temperature control.
The first trick is to adjust the temperature of the water component of the recipe to determine the required initial dough temperature. The desired dough temperature (DDT) we want to achieve is 27 degrees C - the optimal yeast metabolic temperature.
There is a formula used by pro-bakers that takes into account many factors, such as room temperature (the initial temperature of the ingredients), the friction factor that an electric mixer imparts heat to the dough and others. For home baking the formula is highly simplified and is -
81 - 2 X (room-temperature) = water temperature
An example is in order. If the room temperature is 21 degrees C, the formula becomes-
81 - 2 X (21) = 39
In other words we need to heat the water up to 39 degrees C before adding it to the dough, so that the dough temperature (after mixing) will be 27 degrees C.
Another example, if the room temperature is 35 degrees C (a hot day), the formula becomes -
81 - 2 X (35) = 11
In this case the water needs to be cooled down (in the freezer or with ice) to 11 degrees C to obtain a 27 degree C dough temperature.
Note: This formula operates on the assumption that the other ingredients - flour, yeast, salt, sugar etc. are at room temperature. If you keep these ingredients in the fridge or outside, not at room temperature, then the formula needs to be altered (this is beyond the scope of this article).
To measure the temperature of the water you will need a kitchen insertion thermometer, a low priced accessory found in most kitchenware stores.
Controlling the initial dough temperature is the first step to ensure consistently performing dough. It is sufficient for dough that has a rising time of 3 hours or less. For dough with extended rising times of 6 hours or more, like sourdough/natural yeast fermented dough, the initial dough temperature trick of heating/cooling the water is only the beginning.
Following that you need to place the rising dough in an environment which is as close as possible to the DDT of 27 degrees C. This means placing the dough on a warm surface, or a sunny corner of the counter, or more extremely - by heating or cooling the entire room. Professional bakers have a piece of equipment called a proofer that controls the temperature of the dough while it is rising, but this can easily be simulated at home (not with the same degree of accuracy) using your instincts and the simpler means at your disposal.
Now that we have dealt with the temperature factor, the second climatic factor that affects dough behavior is humidity.
As dough rises, it is very similar to an expanding balloon. If the exterior "skin" of the dough is moist and flexible, it will expand elastically as the dough rises. If however, the outer skin of the dough dries out, it loses its elasticity and as the dough rises it will either crack due to the increased pressure from the dough, or if the dried skin is of sufficient hardness and thickness it may even prevent the dough within from rising any further.
This means you will either obtain bread with a cracked, unsightly crust, or bread that has not risen sufficiently, with a dense and heavy crumb.
As long as the relative humidity level in the room where the dough is rising is above 70%, you do not have to worry about this issue. The problems arise when humidity levels drop below 60% relative humidity, i.e when the air is dry.
To prevent the outer skin of the dough drying out in cases like these bakers adopt numerous techniques. The first, and perhaps most common, is covering the bowl of dough with a damp cloth. This preserves the high humidity environment surrounding the dough. Another common solution is to baste the exterior of the dough with oil. This prevents air from coming into contact with the outer skin of the dough and drying it out. Another method is to periodically spray the dough with a spray bottle that emits a fine mist spray to moisten the crust.
To determine the relative humidity level in the room accurately you would need a humidity meter, but you can do this instinctively as well. Most people can detect high humidity levels (like before it rains). The air is moist and can make you sweat profusely (if it is also warm). When the air is dry, you can feel it in your throat and on your skin which may burst out in cracks. Alternatively, you can play it safe and use any of the three methods described above as a matter of course, regardless of what the relative humidity level is, as a precaution.
So we have temperature control, we have humidity control, all that is left is wind factor and barometric pressure.
The wind factor has a similar effect on dough as a combination of the humidity level and temperature - it may dry out the skin of the dough and raise or lower the dough temperature (depending on whether it is a hot or cold wind). You want to place dough away from winds and draughts and preferably keep it covered, to eliminate this factor.
As far as I know barometric pressure has no significant influence on dough behavior. It may affect the behavior of the baker (there is research into how barometric pressure affects your mood and feeling of wellbeing), but dough apparently does not appear to be affected by it.
I am beginning to sound more like a meteorologist than a baker, but I think we have things pretty well wrapped up (excuse the pun). Using the above tricks and techniques you can achieve consistent baking results regardless of the weather.
Keep warm and happy baking.
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